tornado/test/util_test.py

from __future__ import absolute_import, division, with_statement
import sys
import unittest

from tornado.util import raise_exc_info


class RaiseExcInfoTest(unittest.TestCase):
    def test_two_arg_exception(self):
        # This test would fail on python 3 if raise_exc_info were simply
        # a three-argument raise statement, because TwoArgException
        # doesn't have a "copy constructor"
        class TwoArgException(Exception):
            def __init__(self, a, b):
                super(TwoArgException, self).__init__()
                self.a, self.b = a, b

        try:
            raise TwoArgException(1, 2)
        except TwoArgException:
            exc_info = sys.exc_info()
        try:
            raise_exc_info(exc_info)
            self.fail("didn't get expected exception")
        except TwoArgException, e:
            self.assertTrue(e is exc_info[1])